version 0.5 draft syntax

These documents will typically use elements and attributes from the
RDF namespace(s) directly. The namespace for the base RDF model
(defining statements and properties) and the namespace for RDF
Schema (defining classes and constraints) are invoked
with XML namespace declarations of the form:

Here, the type and equivClass arguments
declare the permitted syntax for these elements.
These declarations use XML type declarations from an
XML Schema for RDF,
reproduced in the next section.

The schema declaration for each of the elements above says that they
have the syntax
of an RDF typedNode. A typedNode element is a
short-hand expression for declaring an instance of a Class.
For example,

Note that the syntax for declaring classes and properties shown
in the previous section is also an application
of this same typedNode syntax. "MyClass" was declared
to be an instance of the RDF class
'Class';
that is, it is a Class. And "myProperty" was declared to be
an instance of the RDF class
'Property';
i.e. it is a Property.

This says "there exists a program whose authors are a person
whose given name is "Dan" and no others."
(This English transcription is not precise about
whether "Dan" is the name of the person or the name of
the program. This is a common feature of "natural language",
however the RDF is unambiguous.)

Variables in a expression are identifiers in a reserved
part of the W3C Web address space; there is no special URI scheme
that universally means 'this is the name of a variable'.
URIs beginning with http://www.w3.org/2000/07/hs78/KIF?word=%3f
serve as KIF individual variables. (%3f is the hex encoding of
the character '?'.)

You can read this as "there exists an instance of a weakly true
statement whose predicate is "=>" (implies), whose subject is the
conjunction of the reified statements "x is subOrganizationOf y"
and "y is subOrganizationof z", and whose object is the reified
statement "x is subOrganizationOf z", where x, y, and z are
variables."

Note that we have used a third namespace in this example, an
example namespace corresponding to the SHOE base ontology, to
incorporate a prose description of the rule intended for
human consumption. This illustrates the ease with which an
RDF expression can take advantage of properties defined by
a variety of sources.

A graphical illustration of this rule for the transitivity of
subOrganizationOf is shown below:

[RDF] uses BNF to specify the syntax of RDF XML expressions.
A translation of
that
BNF into XML Schema completes the formal syntactic definition
. An annotated version of
this translation,
sufficient our use, is:

With the two XML schemas above, tools such as
XSV,
XML Schema Validator, can be used to check the conformance of
an XML document to this specification.
Ralph Swick
$Revision: 1.20 $ of
$Date: 2000/08/22 03:21:30 $
by $Author: connolly $
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